Should the Chevy Volt have direct mechanical drive of the wheels...or not?

Engineering products that are meant to be sold to consumers is a process that is invariably about compromise. If you are building a one-off product for a single client, you can optimize it directly for their needs. But when it comes mass production for customers with widely divergent requirements, engineers have to make judgment calls.

Case in point is the Chevrolet Volt and its Voltec powertrain. Within moments after Bob Lutz stepped out of the concept on January 7, 2007, there has been an almost constant discussion about the merits of the E-Flex/Voltec architecture. One of the more notable features is that, despite the presence of an engine in the car, it has no mechanical linkage to the wheels. The engine only drives a generator to provide electricity when the battery reaches its depletion point. The problem is that this so-called "charge-sustaining" mode involves multiple energy conversion processes. One of the first things you learn when you start studying engineering is that there is no such thing as a 100-percent efficient process, and that means figuring out ways to make the best out of what you've got. Continue reading about how the Volt should drive its wheels after the jump.

There is a principle in physics known as conservation of energy. Energy can neither be created or destroyed, but it can be transformed from one form into another. For example chemical energy (the bonds that hold atoms and molecules together) can be transformed into thermal (heat energy) through the process of combustion. Kinetic or potential energy can transformed into electrical energy when, for example, a moving river flows through a turbine connected to a generator.

However, each of those conversions also produces some non-useful (most of the time) forms of energy that is lost in some way. For example, a generator will have both mechanical friction and electrical friction (resistance) that causes kinetic energy to be transformed into waste heat. The same phenomenon applies when electricity is converted to kinetic energy in a motor or you shift between direct and alternating current in power electronics.

All of this brings us back to the Volt. In charge-sustaining mode, we have the following energy conversions (all of which are downstream of the combustion process):

mechanical kinetic energy at the crankshaft to alternating current in the generator

alternating current to direct current for the battery/electric drive

direct current from the battery/generator to alternating current for the traction motor

alternating current to kinetic energy for the wheels

If we conservatively assume that each of these conversions is 95 percent efficient (likely less for some of these) the overall efficiency is 0.95 * 0.95 * 0.95 * 0.95 = 0.814 or 81.4 percent efficient. That means the Volt is likely losing at least 20 percent of the engine's output before it gets to the wheels. A prime example of this can be seen in the power-split hybrid systems used by Toyota and Ford. When driving on the highway, these company's hybrids actually get worse fuel economy than they do in the city in part because the power flow is going through the motors where – say it together now – there is a loss of efficiency.

When driving directly through a set of toothed, mechanical gears, the power transfer efficiency can be upwards of 95 percent. Certainly General Motors is well aware of this phenomenon. That's why, in developing the two-mode hybrid system, GM went beyond what Ford and Toyota did by adding a pair of clutches that lock the motors and provide a direct mechanical drive path. This allows GM's hybrid trucks to get improved highway fuel economy and better towing capability than other hybrid drive systems.

So, why not do this with the Volt? It's about compromise and mechanical complexity. There is no technical reason that the Volt could not have direct mechanical drive and better efficiency. However, doing so would require the addition of a power-split transmission system as well as re-tuning the engine. The Volt engine is tuned for optimal operation at certain fixed engine speeds and only produces about 80 horsepower. To provide adequate performance, the engine would either have to put out more power or blend gas and electric drive during acceleration.

A power-split transmission that can do the blending would add weight and cost and also limit the packaging flexibility. Currently, the Volt uses a simple single-speed reduction gearbox for the electric drive. The engine/generator mounting location is also not tied to the position of the driving axle thanks to the lack of a connection. This would change with direct drive.

When the GM engineers devised Voltec/E-Flex, they worked from the assumption that three-quarters of daily driving is less than 40 miles and most of the rest of the trips are not much more than 40 miles. All of that means that the vast majority of the Volt's real-world duty cycle would fall well within the electric driving range and the charge-sustaining operation would be kept to a minimum. Adding direct drive would undoubtedly improve the overall mechanical efficiency. However, given the design assumptions, adding the extra cost and weight of a power-split transmission would not be justified. The compromises made in the Volt's design are an indication of how customers are going to have to be more thoughtful in their automotive buying decisions in the future. The ultimate efficiency of hybrids, PHEVs, BEVs, ER-EVs and even conventional vehicles are highly dependent on the usage patterns and consumers need to look at theirs in choosing the right vehicle. These are not jack of all trades machines.

We still don't know what the Volt's charge-sustaining efficiency will be or whether the GM engineers made the right decisions. Those answers will only come once we get to spend extended periods with the Volt but hopefully this provides some insight into the decision process.

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Anonymous

2 Months Ago

DB,
Cat uses what they refer to as differential steering. It uses 3 planetary gearsets and it does have a hydraulic motor, but the hydraulic motor is stationary until you start turning, then it turns the planetarys one direction to steer one way, and the opposite direction to steer the other way.

GM's best two-mode hybrids get 22 mpg highway. This is not only worse than any other companyâs hybrids, it is only 1 mpg more than the Tahoe LTZ. [Granted nobody else makes full-sized SUV hybrids, but your statement as written is incorrect, but literally and relatively.]

In comparison, the Fusion hybrid gets 36 mpg, a 2 mpg improvement over the not hybrid I4 and 9 mpg over the more comparable V6. The Honda Civic sedan hybrid gets 45 mpg, 9 mpg more than the non-hybrid sedan. The Prius gets 48 mpg highway, which is pretty much better than almost anything on the market, particularly like-sized cars.

You also say "GM went beyond what Ford and Toyota did by adding a pair of clutches that lock the motors and provide a direct mechanical drive path.â
While this is true for the mechanics, the electrical side of the GM two-mode does not measure up to its one-mode counterparts:
1. GM chose cheaper, smaller (as proportional to vehicle mass) less efficient induction motors compared to Toyota's and Ford's more efficient, more power-dense Permanent Magnet motors.
2. GM chose to stick with a 288 V architecture to save on electronics cost, when its competitors where going to much more efficient 650 V architectures. Low voltages mean higher copper losses. Remember resistive losses are R/V^2.

Anonymous

2 Months Ago

Dave R,

You are incorrect about the two-mode's functionality as was a recent recent review of the 2-mode Silverado that appeared on Autoblog.

The two-modes actually do run on an Atkinson cycle and in hybrid mode, the planetary gear-set runs as a CVT in much the same way that the Toyota and Ford systems do. In fact there are actually two separate CVT ranges for different vehicle speed (that's actually where the 2-mode name comes from). Only at highway speeds do the clutches start to lock up and send the power-flow around the motors through the four fixed ratios, allowing the vehicle to operate more like a conventional model.

Anonymous

2 Months Ago

The point of a range-extended electric vehicle is that you can design the basic electric car as a platform and the range extender can be changed without major changes to the platform. Everyone thinks of gas or diesels piston engines as the typical power plant but you could use a fuel cell or a turbine or even a trailer mounted rental extender.

You just have to wrap your mind around the fact that the extender is decoupled from the wheels.

Anonymous

2 Months Ago

Two reasons why the GM 2-mode gets nearly identical highway fuel economy to it's non-hybrid counterparts is because the transmission has fixed gear ratios and the engine does not run on the Atkinson cycle.

Split power hybrids (like Ford's and Toyotas) have a very elegant CVT which allows very low rpm highway cruising and the engines run on the Atkinson cycle.

For example, look at the 2008 RX400h and 2010 RX450h - the RX400h did not run on the Atkinson cycle and their fuel economy suffered as a result - The RX400h is rated at 25mpg combined while the RX450h is rated at 30mpg combined.

Huge improvement even though the new engine is larger (3.5l vs 3.3l), makes more power (245hp vs 211hp) and weighs 300lbs more (~4500lbs vs ~4200lbs).

Anonymous

2 Months Ago

Sam Abuelsamid:
I do believe David is correct. Atkinson does not have anything to do with the transmission. It has to do with the timing of the valves and how the compression and expansion cycles are handled. Neither the current GM two-modes, nor the Volt use Atkinson cycle engines. The now cancled Saturn Vue two-mode did use an Atkinson cycle engine, but alas, it will never be...

The "two-modes" in a GM two-mode are the "input split" mode and the "compound split" mode. The first has the a planetary between the engine, generator and motor and the motor connected to the wheels. The second has, in addition to the first planetary, a second planetary connecting the output from the first planetary to the motor and the road wheels. GM's system can switch between these via clutches. For pictures see:

Anonymous

Anonymous

2 Months Ago

Yeah, we really need the Volt MPG number. Strange that it has not been released especially considering that we now have the price.

It seems they are either hiding it because it is not so good ("Uh . . . it is 32. OK. Next question.") or they are saving it to use it as a big splash ("And when your battery runs low, you get 50MPG when you drive on gas!")

Anonymous

2 Months Ago

probably NOT true. see Spec's comment, above yours.

Also go read:
http://en.wikipedia.org/wiki/Series_hybrid#Series_hybrid, for a high-level list of trade-offs of each design,
and finally:
I would love ANYBODY to actually post actual data (I don't have it), e.g.
while a sterling engine can be close to perfect in efficiency ... with zero load (sigh) ... a simple calc with actual data on:
1) clutch/transmission,gears weight and friction loss ... and:
2) engine efficiency loss between a single RPM tuned for charging a battery vs. an engine tuned for battery and/or transmission/wheel load...

... and then tally up totally energy loss (inc. lugging all that weight around).
Or ... we stop speculating and wait and see what sort of MPG something like the Volt actually gets with the engine running.

Anonymous

2 Months Ago

Sam:
Another thing you need to correct:
"When driving on the highway, these company's hybrids actually get worse fuel economy than they do in the city in part because the power flow is going through the motors where â say it together now â there is a loss of efficiency."

As you can clearly see, as the vehicle goes faster and faster, less power goes through the series portion of the driveline. At about 65 mph, the Motor-Generator 1 is no longer used. The vehicle is now running purely mechanically, Motor-Generator 2 is used only with the battery power if passing/accelerating is needed.

Anonymous

2 Months Ago

Dear greenlings,

Should I really give a damn about engine efficiency percentages?

What I want to know is how much gasoline the Volt "generator" is using, in comparison to a normal ICE.

As a consumer, it makes much more sense to me if you said "you only fill up 5 gallons" and "that will charge the battery for x amount of miles", vs a comparable 20 gallons or less tank for normal cars.

This is the same baloney that people like to throw around and use against hydrogen vehicles; greenlings need to realize that the average consumer doesn't care in the slightest about the maths or other crap.

They want hard numbers and hard pricing. Give us that, and if it does indeed sound better than your conventional car, then you've made a sale. Otherwise, you're just plain guilty of trying to hide the shortcomings the technology. Prove to these consumers these cars are the better buy, and well, they'll buy it.

Anonymous

2 Months Ago

The original statement still says exactly that. All the quoted statement says is that once the battery reaches a certain level, the ICE comes online. This is common knowledge and says nothing about recharging You are speculating beyond that that the batteries are never charge from that point

The ICE runs a generator that charges the battery. What is so difficult to understand about that? The ICE doesn't not fully recharge the batteries, but it does recharge them to a certain level that's yet to be public knowledge.

quote - "The erroneous information provided by Chevrolet yesterday was today contradicted by John Lauckner, GM's VP for Global Program Management, who says that the 1.4-liter gasoline engine does in fact send whatever surplus power it makes to the lithium-ion battery. The gas engine will never come close to recharging the battery to its operational maximum, however." -

Anonymous

2 Months Ago

@David Martin#25: "What I have against the RE idea is that when the battery is rundown you are basically driving an underpowered ICE and not having much fun."

This isn't true. The ICE is only used to keep the battery charged enough to keep running. You are ALWAYS using electric power to move, and the performance will always be the same whether the ICE generator is running or not.

Anonymous

2 Months Ago

It's pretty difficult to optimize for the Volt, and I reckon they are keeping quiet about the petrol consumption when the battery is low for a reason, and efficiencies are low.
In contrast it is relatively simple to optimise for a through the road hybrid:
'That doesn't sound like much electric horsepower. That doesn't matter: what you really want for acceleration is torque - and electric motors have plenty of that. In this case there's 148lb-ft on tap, which, when added to the 221lb-ft from the diesel engine, gives you have a potential 369lb-ft. And yes, in this hybrid (unlike, say, a petrol-fuelled Lexus RX 450h) the point at which the two power units' torque curves cross happens to be at peak torque for both.

That means the HYbrid 4 really will give a 369lb-ft burst of thrust from low engine speeds, making it a potentially rapid machine. And here's the best bit: all that torque, and a combined 200bhp, comes with a CO2 figure on the official test cycle of just 109g/km. In no other production car can so much power be had for so little CO2 output and a combined-cycle fuel consumption of 68.9mpg.'

The plug-in version of course due in 2012 should be much more considerably electric, and I would like to see something like the SK Energy 7.9 kwh 20 mile electric range battery used in a through the road hybrid.

The torque characteristics of diesel seem very well adapted to hybrid use, and benefit from the fast response characteristics of the electric parts of the power train:
'Even with 4WD not selected, though, the electric motor fulfils other functions: it's on call to help the getaway; it adds acceleration when needed; and it smooths out the shifts in the manual-based (but automatically controlled) six-speed gearbox by ladling-in torque when the diesel engine's drive is momentarily severed. '

Nissan with their hybrid design will have to go some to beat it in my view.

Anonymous

2 Months Ago

You are of course correct. I should have said that for highway driving the acceleration tapers off substantially at higher speeds whatever the state of the battery.
The larger engine in a Hybrid 4 will produce much more brisk acceleration using the electric motor to help.

Anonymous

1. With an all electric drive train, future battery improvements can extend the EV range (and the mileage)

2. With an all electric drive train, any number of alternative technologies can be used to charge the battery, and none without impacting the ability to drive the vehicle. (REMEMBER: The 2.4L gasoline engine used today was done so to simplify developement by using off-the-shelf technology)

With an all-electric drive the Volt still has the potential to be a game changer.

If you add mechanical drive, the Volt is simply another hybrid........

Anonymous

2 Months Ago

What I have against the RE idea is that when the battery is rundown you are basically driving an underpowered ICE and not having much fun.
With a Hybrid 4 you are driving an ICE augmented by an electric motor for better fun, and still have a diesel engine which is great for long runs, but even further optimised by peak power coming from the electric motor, also usable as a pure EV at low speed for a couple of miles or so.
You are loosing some power by using the ICE to charge the battery, but most of the gear is there doing a job which it is pretty optimal at.
So how easily can that concept be moved on as more powerful batteries become available?
Pretty easily actually. The first step might be to use two electric motors for each wheel at the rear, so keeping the electric motor to a good size and avoiding the need for a differential.
By that time the expense of the control system needed should have decreased.
When much better batteries are available or fuel cells, preferably high temperature, improve enough to permit an all electric drive train then the ICE could be substituted out reasonable simply one would have thought, as it operates independently of the electric motor.

Anonymous

2 Months Ago

I was in error in saying that the Volt performance would differ when the battery is depleted.
The small engine running at constant speeds is likely to give it poor acceleration at higher speeds whatever the state of the battery.

Anonymous

2 Months Ago

This is not a reply to anyone in this conversation, but back to the original question about whether the Volt should have direct drive to the wheels.

Caterpillar has recently come out with a dozer that is very similar to the Volt in how it was designed, about the only thing different from the Volt is the Cat D7E doesn't have a battery pack, just enough battery to start it. Other than that it is a Diesel motor hooked directly to a generator, and 2 electric motors do all the work at the tracks.
Cat's testing shows that this D7E is 25% more efficient than their conventional transmission equipped D7R. Cat contributes this to the generator and electric motors being more efficient than the conventional transmission/direct drive is.

Quote from Cat: "The electric drive system puts engine power on the ground more efficiently than any other drive type"
(And Cat has done extensive testing to back this claim up)

Anonymous

2 Months Ago

mail:
Most of the tracked drive vehicles I've looked at have hydrostatic drives, which are extremely lossy. Think of a car transmission that was all torque convertor and no gears. A series hybrid would clearly be an advantage here. Also tracked vehicles have very high rolling resistance, so regen would not be feasible (hence no hybrid battery).

What I don't think is playing a big part in the efficientcy gain is this system keeping the engine at a particular rpm. CATs use pretty modern diesel technology. Their specific fuel consumption curve is fairly flat compared to gas engines. This means that they can run efficiently at different RPMs and loads without too much loss in efficientcy.

As a side note, Komatsu, the World's second larger earth moving equipment manufacture, has focused on regen for the swing arms on their excavators.

Anonymous

4 Years Ago

Snowdog:
The Volt is clearly a more capable as a pure EV that the Prius. No doubt. However, "better" is a subjective term is determined by the market and by your use case of the end user. Your "better" is likely not my "better".

The Prius is cheeper and more efficient running on either strickly electric or strickly gasoline. It is has 5 seats instead of 4 and more available safety gadgets (i.e. CMbB, LKA). There is no hard reliablity data yet, but the Prius is based on a mature design and its batteries have been in development and testing for much longer. These are all factors I consider when I am deciding if A is better than B.

To figure the "Best" EV you must consider use case. If you need more than 40 miles but less than 100 of pure EV range, the Leaf is likely the best. If you need less than 40 but more than 15 the Volt is likely the best. If you need less than 15 miles (like 80% of Japan, and many places in Europe and Asia) the Prius plug-in is likely the best.

If you want EV + gas capablity, you will have to run an analysis of your driving cycle, and figure out which (Volt vs. Prius) would provide the best value for your use case. Keep in mind you have to factor in the purchase/lease price into this equation.

Also the modifications I mentions would not require "reengineering" the Prius. These modifications are substantially less than went into making the Prius a plug-in in the first place. The motor-speed can most likely be addressed in software, as it was going from the regular Prius to the plug-in. A different battery pack would be required, but I suspect that is already under development.

Anonymous

2 Months Ago

David Martin:

With all due respect, the only things the Nissan/Korean battery manufactures are leading in are press releases. Today, the combined capacity of LG-Chem and Nissan only make about 8% of the Worldâs Li-Ion batteries. Panasonic/Sanyo, by far the largest producers of Li-Ion batteries, has approximately 40% of the World market share. They have more Li-Ion patents and are spending more $ on R&D and factory capacity than anyone else. Also Sanyo is the only battery maker with long-term experience with automotive Li-Ion batteries. (They made the Li-Ion battery for Toyota's Vitz mild hybrid from 2003-2008 and have 4 years/6.5 million miles of testing on the new Prius plug-in.)

The Japanese press has all but confirmed Toyota's switch to Li-Ion. In addition to the Prius plug-in, the Prius wagon, new LS hybrid, and a Li-Ion minivan (Estima?) have all been confirmed for the next two years. In addition to Toyota Panasonic/Sanyo already have deals to supply Li-Ion batteries to VW/Audi, Suzuki, Mazda, Tesla, and Yamaha (motorcycles). They will also be supply Li-Ion batteries to some of Toyotaâs non-automotive businesses.

Last year Sanyo sold about $3 billion US in Li-Ion batteries. If you assume $1000/kwh this comes out to 3,000 kwh. Panasonic announce that the plan to triple the combined company's capacity by 2015.

Shortly before the Panasonic deal last December Sanyo had projected that they would have 40% of the automotive Li-Ion market by 2020. While this may be a projection, so too are Nissan's numbers. The major difference is that Sanyo already makes thousands of kwhs of batteries a year and Nissan is a total newbie.

To date Nissan nobody is selling a mass-market EV, so a realistic market size for pure EVs is only conjecture. Remember, GM promise that it would sell a million EVs by 2010 [granted GM and Nissan are on different ends of the credibility scale].

Anonymous

2 Months Ago

Actually the argument necessarily is about who can build a better hybrid.
Both the Prius and Hyundai use very different systems to the GM series hybrid, and from what we know IMO both are likely to be better solutions.

Anonymous

2 Months Ago

David Martin:
Toyota has not announced the details of the Prius Wagon, other than it will be bigger than the Prius have a Li-Ion battery. I feel that it is a pretty solid bet that it will be bigger than the 4 kwh Prius pack, but probably not as big as the Volts. We'll have to wait and see I my hunch is correct.

Right now the biggest trade-off for range is really the prohibitive cost of the battery pack. If one company could corner the market on Li-Ion, they could offer a much better range/$ value then their competition.

Look at the NiMH market. Toyota was able to corner 80% of the automotive NiMH market (through 80% ownership of Panasonic EV, renamed Primearth) and the remaining 20% they influence through partial ownership of Sanyo. Now other companies like GM have to buy from Toyota, virtually guaranteeing Toyota gets the best price and that they profit off of their competitors.

GM and Ford are buying from LG Chem, which (last time I checked) had ~8% of the World Wide market (automotive and non-automotive). Toyota is buying from Sanyo which was recently bought by Panasonic, a company that Toyota has a large percentage of ownership. Combined Panasonic/Sanyo have 43% of the World Wide Lithium-Ion battery market. Sanyo recently announced $2 billion in Li-Ion expansion and Panasonic is believe to be hording about $9 billion to finish the purchase of Sanyo and for its own expansion. This investment, it is believed, will give the new company over half of the World-wide Li-Ion market within two years.

Combine this with the fact that Toyota recently bought 25% of the World's highest capacity Lithium Carbonate mines (over 30% of the World's capacity). It is pretty clear the Toyota and its gang are presently trying to corner the Li-Ion battery market the same way they did with NiMH.

I find it hard to believe that, with all this investment, Toyota isn't planning something huge with Li-Ion batteries in the near future.

Anonymous

2 Months Ago

DB,
Even if Toyota switch all their battery production to Lithium, which in my view there is no indication of at all, a pack for a hybrid is a very different matter to a full EV pack, so they might have an output of around 3million kwh or so, a fraction of Nissan's.
The ones who are leading are Nissan and the Korean companies, LG Chem and SK energy, who have taken nearly all the business from other car makers.
The exception is Peugeot/Citroen, who are using Panasonic, but it is their NiMH batteries.

The Obama administration is fantasising with their talk of a 40% share in battery production.
Part of the reason for the battery factories being built around the world and not just in Japan and Korea is that they are fairly heavy and it makes sense to produce them near where they are used.
The other reason is of course political, the desire of countries to build the batteries on their own territories.
The notion that this desire to build the batteries at home is peculiar to America is American exceptionalism at it's most naive.
The biggest car market in the world is China, and by 2015 it will be by far the biggest.
They are not going to use American batteries to substantially power their EV fleet.
Most of the batteries will be produced right home in China.
Ties with Japan and Korea are becoming so close that they may allow considerable imports from those countries, but by and large they will have to set up production facilities in China.

The drive to encourage battery production in the US is a good one in my view, but the rationale given is a pipe dream.

Anonymous

2 Months Ago

David Martin:
You may be right. Nissan will certainly give Toyota a good fight. [They always have] It won't stop Toyota from trying its best. My point is that Toyota's up to something. Unlike GM and Nissan, they don't publicize their internal strategies.

If the majority Toyota hybrids switch to Li-Ion by 2015, as Nikkei speculates they will, Toyota could make close to 2 million Li-Ion packs a year. This seems consistent with the investment Panasonic/Sanyo is making. Even if Toyota can't push Nissan out of the market, together they will likely push out the other small fish. (Compact Power? A123?) I expect there will only be 4 or 5 serious players in 2015.

As of the Chinese, the only company that keeps me up at night is BYD. They are planning on spending $3 billion over the next few years. Given how much cheaper tooling and labor is in China, this might has well been $10 billion anywhere else.

One thing I feel is fairly certain is the $2.4 billion Obama spent on US battery manufacturing will not give the US the promised "40% of the world-wide market in 5 years". 10% would be pushing it.

Anonymous

2 Months Ago

Hyundai seem a likelier candidate to build a PHEV with enough range in pure electric mode to compete more squarely with the Volt.
Their Blue Drive seems to be a variation on through the road drive rather than using a Prius type arrangement or serial drive, and their battery supplier SK energy has developed this pack:
'SK has assembled three sample PHEV packs and is currently designing a compact 360V, 7.9 kWh pack, targeted at a 20-mile all-electric range PHEV. The PHEV20 pack uses 96 cells and is 65 liters (0.065 cubic meters or 2.3 cubic feet) in volume.'

Anonymous

Really the Prius is in the discussion as an engineering example, not a who can build a better hybrid argument. The question is should GM have a more hybrid like drivetrain?

I Say NO!

If GM had built a power combining drivetrain like the Prius, it would have been a bit heavier and more expensive for little point.

A 10% mechanical loss on a drivetrain is actually a good comparable result, it is likely GM doesn't lose much more than 15%. Having a heavier/more complex drivetrain for 5% on range extender duty, since the cars real mission is to use the range extender as little as possible, is really pointless.

Anonymous

2 Months Ago

DB,
With Nissan/AESC producing 550,000 battery packs by 2015, around 13million kwh or so a year, Toyota and Panasonic won't be cornering the lithium battery market anytime soon!
China also has substantial lithium reserves in Tibet and is doing a deal with Burma to link them in to the 17 country high-speed rail network they intend building by 2020 in exchange for access to their lithium reserves.
South Korea is putting $26 million into developing lithium from seawater technology, and hopes to be producing 20,000 tons a year by 2015.

Anonymous

2 Months Ago

DB, Sanyo certainly sells a lot of rechargeable lithium batteries, but that is mainly for laptops etc, and is of a different order of magnitude to mass produced car batteries, as I don't believe the Vitz sold a lot.
The 3,000 kwh of Sanyo compares to in Japan the factories AESC/Nissan are building for 90,000 EV cars a year, or around 2,000,000 kwh.
OK, maybe they will screw up, but the whole thing is of a totally different order to the production Sanyo/Panasonic have been doing to date.

Anonymous

Sorry for the bad math. $3 billion / $1,000 per kwh = 3,000,000 kwh in 2009. 3,000,000 kwh in 2009 > 2,000,000 kwh in 2015. If Pansonic's projections are then they will sell 9,000,000 kwh in 2015.

Yes, the Vitz was really low volume only a few thousand sold over 5 years. This is still more experience than anyone else has to date. The whole point of the Vitz getting a Li-Ion battery was for Toyota to experiance the issues of Li-Ion in automotive use cases. This data is gold for anyone who wants to get into the automotive Li-Ion battery market.

If NiMH can teach a lesson, the biggest issues that Panasonic faced when converting over from consumer electronics NiMH batteries to automotive NiMH batteries was about a thousand-fold decrease in defects of its battery manufacturing process. In 1996 Panasonic was not up to this task, so Toyota actually had to take over manufacturing management from Panasonic, and put in its own guys. I suspect why Toyota started the Vitz hybrid so early in the game was to shake-out all the quality bugs.

Anonymous

2 Months Ago

Yes definately! Adding a dual clutch power blending transmission would greatly simplify the design and improve reliability. It would be great because then you could hear engine reving more as it struggles to stay in its power band and the gears shifting with a slight power lag between shifts.

That would make the volt awesome in ways that EV enthusiasts just don't understand!

Anonymous

2 Months Ago

A serial hybrid is in essence a separate two module car, running on the batteries until they are depleted and then running the engine as a genset to directly run the electric motor. I don't know how the car is designed; but, seems to me that removing the complex ice engine and its necessary extra weight of the fuel tank, clutch, exhaust,etc., and replacing them with extra batteries would be easier on a serial hybrid and would turn the car into a BEV. Perhaps this is part of the thinking for the Volt,i.e., as the battery technology progresses and hopefully the prices of batteries go down, at some point, they will have the courage to change over it over.

Anonymous

2 Months Ago

Peugeot reckon that their through the road system uses the electric motor to smooth the gaps in the automatic box, so the power is always there.
At the moment Geen Car Congress seems to be playing up, so I can't confirm with the links as I believe the specs were on there.
You are carrying the extra weight to split the power to charge the battery of course, but the mild hybrid Peugeot has gone for using a diesel engine seems to get decent highway mileage as well as in town, and of course 4wd.

Anonymous

2 Months Ago

Paul, I take it that you are being sarcastic?

but more importantly, Sam, if you are listening, which you never do which is why you wrote this very incorrect article.
first of all, the Volt does indeed have it all connected, ICE, generator and motor with planets gears and a number of clutches. you say they are separate. that's just not true.
we also know from the german Opel engineer that the Volt is physically capable of closing a mechanical connection from ICE to wheels. the exact reason for that design is unknown, this would be the kind of thing you would want to ask GM..

additionally you assume rather convenient efficiency numbers and scenarios for the mechanical coupling. the 95% I presume is picked out of thin air and it overlooks a very key aspect which is that the ICE is only peak efficient at certain rpm and torque levels. this is actually why normal gas cars suck at city driving and is the entire basis for the merit of the prius in that the funky planet gear can keep the ICE in a happy place. quite the contrary to your conclusion about the prius.

as to the efficiencies of series conversion losses, from AC to DC can be done well above 99% in the simple case. good power electronics is probably 99% efficient at DC to AC too, even higher if you really go for it. as for gen/motor those are actually often only 85% but that's piss poor design although common. let's say 95% with good permanent magnet design. say combined 89% efficiency which then is hard for the mechanically linked version to beat because of nasty gears and ICE sweetspot. with series it runs independent of vehicle speed so can stay at efficient points (in the simple case).
I understand the idea that it must be more efficient to drive the wheels directly from ICE but it's not as simple as that.
given the clean design of series hybrid and the efficiencies possible, I think it has to be the winning drivetrain. that said, a prius style drivetrain with an extra clutch so the one electric motor can drive the car independently of the ICE is likely also a rather efficient solution so you get prius ICE numbers and pure electric drive. ironically that appears to be what the Volt actually is even though curiously they have chosen that the ICE will never mechanically drive the car even though it technically can. as the german Opel engineer said and the GM PR douches indirectly confirmed by not denying the mechanism he described and even verified several critical details of his account.
as you can see from mock up display models of the Volt the electric motor, generator and ICE is bunched together.

the Volt appears to not have great ICE mileage but that's presumably because they used a random ICE not optimized for the job and that the car is heavy. one can speculate that they have been similarly sloppy on the efficiencies elsewhere.

instead of this article promoting mechanical coupling from ICE to wheels we need someone to ask GM in no uncertain terms what exactly is the drivetrain layout and why

Anonymous

2 Months Ago

Dan

Apparently you have issues with basic reading comprehension. First I never said the engine was 95% efficient, that would be an utterly ridiculous statement. A basic toothed gearset transmits torque with 95% efficiency. The engine is probably at best 30% efficient.

Secondly, the so-called Opel "engineer" was a vehicle prep technician that didn't know what he was talking about. There is no mechanical connection from the engine to the drive system in the Volt and GM officials have made that clear.

As for the other efficiency numbers they were not meant to indicate what the volt could but only to illustrate my point about the increased losses as you stack up inefficiencies. That is four 95% efficient systems in series add up to a total system efficiency of only 81%.

Finally, I made no absolute conclusions about whether the Volt should or should not have mechanical drive. I simply explained the rationale for why it might or might not make sense. At this point we don't known enough about the car's performance to make a judgment one way or the other.

Anonymous

2 Months Ago

Sam, sigh et tu.
you have the problem with reading comprehension. try not to so grossly understimate me again.
I didn't say that you said the ICE was 95% efficient. I specifically said mechanical coupling. that's not a euphemism for combustion engine..
you REALLY should take more time to read what I write.

And the guy from Opel was not just a car handler. a car handler doesn't speak out about intimite drivetrain details and future options. and GM substantiated several of his claims and very key, did not deny what he said. if you stopped to think that should tell you a lot.
my reading comprehension is outstanding. read what I wrote.
eventually it'll be obvious that I'm right, better to deal with it now than continue articles on incorrect perception. and as I said, as you can see in the drivetrain display models of the Volt, the ICE and electric motor are all in line and in the same place. that's not necessary in an actual series electric.
stop to think. you seem to be very hasted.

then inquire with GM what the actual Volt drivetrain layout is. the answer should be enlightening.